In general, the measurement of the chemical oxygen demand for water commonly uses a potassium bichromate method which must add chemicals and an electrochemical measurement method which must use a contract electrode. However, the chemicals added in the potassium bichromate method and the contract electrode used in the electrochemical measurement method will influence the reaction time and the stability of the system, and cause the issues of hardly maintenance and operation and poor measuring quality.
In addition, the commercial instruments measuring the suspended solid concentration utilize optical measurement scheme to perform measurements the single-wavelength absorbance to perform analysis. However, the analysis of the single-wavelength absorbance is not suitable for the measurement of variety of different particle sizes of suspended particulates.
The heavy metal mainly comes from a traditional industry, an electroplating industry and a printed circuit board (PCB) industry. The heavy metal pollution such as a copper, a nickel, an iron, a zinc, a chromium and a cadmium pollution, is more harmful than other organic pollution because the heavy metal or the metal compound thereof is not easy to degrade or reduce its concentration by a physical, a chemical or a biologic reaction in the nature. In the wastewater treatment system, the excessively high heavy metal concentration in the waste water will poison the microbe which causes the treatment system unable to function normally. Therefore, how to control the concentration of the heavy metal in the water to further enhance the treatment effectiveness, and to reduce the total quantity of the heavy metal for protecting the ecology of the water is an important topic.
The study of the heavy metal measurement can be divided into three technologies, which are the developer addition technology, the improvement and development of the analysis equipment technology, and the biochip technology. In developer addition technology, the method in this technique can measure only one type of metal, and its reagents cost expensive. Moreover, the developer addition technology has issues on waste liquid generation and treatment. In the improvement and development of the analysis equipment technique, the equipments cost expensive and must consume massive amount of water to perform analysis. The method of the equipment also needs to gauge the range of the concentration by artificial way to establish a calibration curve for every kinds of heavy metal which results in a relatively longer measuring time and causes artificial inaccuracy. In biochip technique, the measurement thereof can be performed more accuracy for copper ion in present. However, the biochip technique cannot obtain a plurality of the data of the heavy metal concentration simultaneously and would be interfered by the particles easily.
U.S. Pat. No. 5,224,634 discloses that a chelating resin having a specific functional group makes the water sample through the open chelation column chromatography to detect the transition element or the rare element in the water sample. U.S. Patent Publication No. 2009/0263907 A1 discloses using a reagent colorimetry method to measure the heavy metal concentration in the water sample such as waste water in the environment. However, these two patents use developer addition and chelating agent respectively which are combined with heavy metal to make the aqueous solution produce color. Then the two patents determine the concentration of the heavy metal according to the depth of color, which causes secondary pollution to the environment.
In wastewater treatment, the heavy metals are commonly measured by the fast heavy metal measurement detector or atomic absorption (AA) spectroscope. However, the detector or spectroscope cannot obtain real-time, accurate and effective monitoring information to satisfy the demands for control. Therefore, it is an important topic to develop a measuring device and method for measuring the heavy metal by various dilutions and scans to remove suspended solid (SS) and chemical oxygen demand (COD), so as to obtain the concentration of the heavy metal such as copper, nickel, iron, zinc and chromium.
In the past, the most optical schemes used in measuring the water components, such as COD, ammonia, heavy metal and SS, can measure one item only, and the measuring range and accuracy thereof are typically limited by the turbidity and SS in the water. The most of the conventional measuring methods utilize a single wavelength or select a better wavelength in the various estimated results to measure the component in the water. Due to the component will interfere, compete and shelter to each other in every components when there are many water component, such kind of measurement technique will not obtain a better measuring result.
It is therefore attempted by the applicant to deal with the above situation encountered in the prior art.